I always use the Salsa but they do get gouged up in nasty conditions. The Syntace superlock looks interesting as it seems to have some sort of bush between the two surfaces unlike the Salsa. The Tune Wurger also looks interesting as it runs on an internam cam rather than an external one. Salsa are the best looking though!

As a serial seatclamp wrecker, I can tell you for a fact that no aftermarket seatclamp is anywhere near as good as just about any O/E clamp that comes fitted to a bike (And I've tried them all. Those Woodman ones in particular are very poor)